Answer: there are three different methods of determining the age of a landform.
1 radiation measurement
2 stratigraphic superposition
3 the fossil record
by using these or a combination of these they determined that the earth is around 4.6 billion years old. and this is where the big bang theory comes into play.
To determine the relative age of different rocks, geologists start with the assumption that unless something has happened, in a sequence of sedimentary rock layers, the newer rock layers will be on top of older ones. This is called the Rule of Superposition. ... With absolute age dating, you get a real age in actual years
the reactivity of alkaline earth metals increases from top to the bottom of the group, that's because the atoms get bigger from the top to the bottom so the valence electrons are farther from the nucleus.
